Environmental Environmental (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Loss Contingencies [Line Items]
Environmental remediation expense	$ 25	$ 300	$ 400
Accrued environmental expense		5,800		$ 6,300
Accrued environmental expense, noncurrent		3,800		$ 4,300
Affiliated Entity
Loss Contingencies [Line Items]
Accrued environmental expense		$ 500